1. Field
This invention relates to a liquid delivery apparatus susceptible for rapid priming and rapid flow of liquids through the apparatus.
2. Prior Art
The are situations where it is desired to be able to transfer liquids rapidly by gravity flow from a container through a conduit and into a collecting container or cavity. For example, it is often desireable to administer simultaneously solutions of amino acids, carbohydrate, and fats to patients by the intravenous (I.V.) route to provide total nutritional needs. In current practice, a hospital pharmacist will add 500 ml. from a bottle of dextrose solution to a liter bottle containing 500 ml. of a solution of amino acids, conducting this operation using aseptic technique in a laminar air flow hood. Vitamins and essential minerals may be added to the mixture. The mixture is then transported to the patient for intravenous administration. A nurse may then introduce a fat emulsion into the administration set to mix with the amino acid-dextrose mixture as it flows through the set to the patient. This procedure must be repeated generally every eight to twelve hours and is time consuming for both nursing and pharmacy personnel.
A large volume flexible pooling container is commercially available for collecting by gravity and mixing distinct nutritional solutions stored in separate smaller containers to provide for a 24 hour supply. The large pooling container is in the form of a bag having at one end a slot for suspending the bag in a vertical position and at the opposite end two sealed inlet ports and a length of I.V. tubing with an inner diameter of about 0.11 inch. The tubing is connected to a Y-adaptor from which extends two shorter lengths of the same size tubing each of which is joined to a pointed cannula. To fill the pooling container for a 24 hour supply, the pharmacist inserts one of the cannulas into a bottle of amino acid solution and the other cannula into a container of dextrose solution, 50% for example, each containing 500 ml. of solution. The containers are suspended, clamps on the tubing are released and the solutions then flow into the pooling bag. After the containers are emptied, the cannulas are removed and reinserted into two more containers of solution and drained into the pooling bag. This process is repeated until the bag is filled with a day's supply of solution. In addition to the attention that must be given to see when the contents of two containers have been drained so that two more containers of solution can be installed for drainage, the time lapse for filling a three liter bag, for example, is on the order of about 21 minutes. The entire operation also should be conducted in a laminar air flow hood to reduce the chance for contamination since the cannulas are exposed to the environment each time they are withdrawn and reinserted. After the bag has been filled, the pooling tubing near the inlet into the bag is clamped and the remainder of the pooling tubing is severed. The pooled contents are then delivered to the patient where a nurse arranges it for I.V. administration by entry into one of the sealed ports. An additive solution such as insulin or one having a relatively high specific gravity, can be introduced into the bag through the other sealed port. However, unless the contents of the bag are thoroughly mixed, after such an introduction, there is a tendency for the additive to settle around the port leading from the bag so that the patient would receive the medication in concentrated form. This could have serious consequences.